[Insight-users] Can't read DWI file (NRRD format, from MIDAS dataset)

[Tiago Brizolara da Rosa]

Hi all,

I'm trying to read a DWI from MIDAS dataset (01025-dwi.nhdr, with data located in 01025-dwi.raw.gz) and I'm getting an exception that ITK throws at itkNrrdImageIO.cxx, line 263:

  if (nrrdLoad(nrrd, this->GetFileName(), nio) != 0)
    {
    char *err = biffGetDone(NRRD);  // would be nice to free(err)
    itkExceptionMacro("ReadImageInformation: Error reading " 
                      << this->GetFileName() << ":\n" << err);
    }

It happens two times reading this file. If I don't catch the exceptions, the header information is read correctly, but the image content is not read.

But in the same dataset, the mask image, also in NRRD format (01025-t2w_mask.nrrd, wich includes the data in gzip encoding in the same file), is being read correctly. I compared both sessions and saw a difference between the two cases:

- while reading the image that works (01025-t2w_mask.nrrd):
In formatNRRD.c, line 145 nio->dataFNArr->len is 0, so the else if (nio->dataFNArr->len) is skipped

- while reading 01025-dwi.nhdr/01025-dwi.raw.gz:
nio->dataFNArr->len is 1. Then, if (nio->dataFNArr->len) is entered. Then fname becomes "./01025-dwi.raw.gz" and, then, the function returns an error, that is propagated and then the mentionated exception is thrown.

I hope I put some useful information and I would be very glad for any help!

I'm using: ITK 3.8 (we can't upgrade now, but if someone knows any fix for this issue in newer versions, let me know); Windows 7, 64-bit; Visual C++ 2010

Thanks in advance,


Tiago Brizolara
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